Large change in water pressure and whining/humming pipes

[floob]

Hi,

I've noticed that over the past few months that when the water pressure reads at around 0.5, when the heating (gas central heating) comes on the pressure changes to about 2. Is that a normal jump in the reading? I dont remember tracking it before, so I'm not sure how long its been that different for.

I ask as now when the heating comes on, there is a definite "hum" or audible "whine" (which can be just enough to wake you) which I'm pretty sure wasn't there, say, last year. I also think the noise is more prominent for the first hour or so.

I would also say that the water pressure (say if I topped it up to "1" used to stay there for the best part of a year, whereas now I seem to be topping it up every couple of months or so.

The setup is currently a gas boiler that heats my water tank. The equipment is around 30 years old.

Thanks for any pointers towards the noise culprit.

 

[oldbutnotdead]

Sounds like the expansion vessel needs pumping back up to pressure. Its very likely inside the casing, get it checked on the next service.
The noise will be a rubber pipe mount either come a bit loose or the rubber has lost its bounce with age. While the noise is happening, hold or lean on the pipes as near the pump/boiler as you can, see if the noise changes.

 

[floob]

Hi,

Thanks for the feedback.
The plumber actually arrived yesterday and "let out a lot of air" from radiators, and increased the water tank pressure from about 0.5 to 1.5 and said if it drops more quickly than usual it would point to a separate problem.
We think the noise may have been originating from the boiler itself rather than the pipes, and it does seem to have decreased quite a lot, although not completely gone, but much improved.